1. Field of the Invention
The present invention relates to devices for measuring the properties of soil, and particularly to a device for measuring expansive soil shrinkage.
2. Description of the Related Art
The swelling-shrinkage capacity of soil refers to the extent that soil containing clay minerals will expand (i.e., swell) when wet and contract (i.e., shrink) when dry. The amounts of certain clay minerals present in the soil tend to directly affect the swelling-shrinkage capacity of soil. Soil with a high swelling-shrinkage capacity is problematic and is known as expansive soil. The ability to drastically change volume can cause damage to existing structures, such as cracks in housing foundations or the walls of swimming pools.
The swelling of expansive soil is usually measured experimentally only in laboratories by using odometers or tri-axial devices. These systems allow only for measuring the swelling under the effect of water pressure and air suction surrounding the sample. In other words, the swelling mechanism is artificially simulated by using disturbed soils samples. These samples, however, typically cannot represent the soil in nature, especially since the soil microstructure and the compaction factor are completely different than what exists in nature. Additionally, these systems not only take a long time to carry out the experiment and get results, but also cannot be done in the field. The time required to carry out one experiment takes approximately one month. Further, the systems measuring the swelling behavior of soil cannot simultaneously test the shrinkage behavior of the expansive soil. As such, existing systems can only measure the swelling behavior of expansive soil, which cannot represent the cyclic behavior between swelling and shrinkage of expansive soil.
Thus, a device for measuring expansive soil shrinkage solving the aforementioned problems is desired.